Year	% of total fuel combustion
1971	2.6373626373626373
1972	2.6692708333333335
1973	2.658959537572254
1974	2.6215182960131074
1975	2.435530085959885
1976	2.559934985778139
1977	2.8411083830235007
1978	2.8228228228228223
1979	3.585417294365773
1980	3.6383092562867843
1981	3.702795487984308
1982	3.9153915391539145
1983	2.1748681898066784
1984	1.7301847089081126
1985	2.3750840241989706
1986	1.046511627906977
1987	2.535983550376972
1988	1.9547551065231719
1989	2.8205684530266857
1990	1.1122095897182416
1991	1.0006671114076042
1992	0.9239653512993268
1993	0.9226983801517318
1994	1.0283363802559422
1995	1.1103993166773443
1996	1.0283755475147593
1997	0.9855564995751916
1998	5.549792531120332
1999	3.502008032128514
2000	4.65641952983725
2001	3.673749143248802
2002	2.6973942647636506
2003	2.174465920651069
2004	2.6772247360482644
2005	3.4416365824308066
2006	4.911220249338874
2007	5.496588324488249
2008	4.116477604958485
2009	1.8163722318984818
2010	5.847830643470972
2011	5.074037512339585
2012	6.69548422698427
2013	7.073082489146164
2014	6.453072676260294